Fatty acids are the major source of carbon fuel for energy metabolism in heart muscle and control of the pathway of fatty acid metabolism under normal and pathological conditions is not well understood. Alterations in fatty acid metabolism do occur under many pathological conditions such as ischemic heart diseases and diabetes and other hormonal alterations as well as during normal growth and development and with aging. Detailed information on the control of each process involved in fatty acid metabolism will facilitate our understanding of the importance and the mechanism of the alterations that occur in the disease states.